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About RCgothic

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    Spacecraft Engineer
  1. SpaceX Discussion Thread

    I mean there may be volatility issues with sealants or materials or such that you'd only discover in a true vacuum test. For pressure vessel integrity I completely agree that 3bar should be good enough.
  2. SpaceX Discussion Thread

    Yup, that's how I'd do it.
  3. SpaceX Discussion Thread

    In terms of pressure differential I'm sure three atmospheres would be fine, but there may be other factors that can only be tested in a near vacuum environment.
  4. What's asparagus got to do with space flight?

    An asparagus has leaves overlapping in a spiral pattern. For an asparagus staged rocket with a large number of stages, the stages usual end of dropping off in a spiral pattern.
  5. Honestly I doubt there's an analytic solution for Pn engines. I envisage a program where you step through every possible combination of engine thrusts in 10% increments for combinations of values close to zero on all but the 1 degree of freedom you're interested in. Then iterate at a finer resolution around those values. Repeat for each degree of freedom. It's a brute force approach but should give you a solution of there is one. May miss 'spiky' solutions where equilibrium is reached very quickly from an unlikely combination.
  6. Not an easy problem! You need to work out what combination of engine thrusts provides rotational equilibrium. As others have mentioned there may be more than one unique solution. Then you either want the axis (solution) in which you get maximum thrust or maximum ISP depending on whether or not you are fuel limited or time limited. Over any reasonable time period the answer will always be to first rotate the axis of maximum engine thrust or maximum isp onto your custom vector.
  7. Mars in three years

    I have no doubt we could manage it with current tech. The problem is budgets and timescales. On current budget the timescale is not getting any closer to the present. On budget max you'd still need to design build and test the interplanetary hardware before the next Mars window, as SLS is not nearly sufficient. That's not happening, as there's too much to do. Even the window for a first interplanetary unmanned test after that is only 2020, which is really pushing it. Finally even if that goes perfectly you need to wait again for the next window in 2022. That's April 2023 manned arrival at Mars at earliest.
  8. Is New Glenn economically viable?

    Yes. Falcon 9 almost gets away with it because second stage does most of the work of getting to orbital velocity. Falcon Heavy first stages lift more payload to a little faster than Falcon 9, but the 2nd stage really struggles. Half as much DV or less.
  9. SpaceX Discussion Thread

    From what I've heard on Reddit, it was a ridiculously close call and insiders say they're not going to release it for PR reasons. Firstly, look at the scorch trail across the barge. Also the last frame shows spray being kicked up way off the mark. The rocket clearly pulled some crazy last minute manoeuvres. Secondly, insiders describe the booster balancing on one leg and nearly toppling. There is also a reference to CRS6 and the little thruster that couldn't. Apparently this time it could. So the video sounds ridiculously awesome, but don't hold out any hope for a release!
  10. Is New Glenn economically viable?

    New Glenn is projected at 45t to LEO and 16t to GTO reusable. It will never fly expendable. Falcon Heavy is projected at 8t to GTO reusable. Payload to LEO reusable is speculative. To match New Glenn 16t to GTO at least the center booster need to be expended (possibility). Falcon Heavy has the potential to beat New Glenn flying expendable, but that's not really comparing like to like.
  11. SpaceX Discussion Thread

    If they can stick the landing with accuracy, maybe they'll be able to build a freshwater /de-ionised landing pool?
  12. Forum designs new rocket to replace the SLS

    Of course the poor dwell time of the hydrogen EUS means you won't be assembling anything in LEO, which limits SLS to small high energy payloads. It's basically useless for anything else.
  13. SpaceX Discussion Thread

    I think there's also a slight plane change manoeuvre required, which is cheaper at higher apoapsis.
  14. SpaceX Discussion Thread

    Can we back calculate what the maximum payload to the minimum GTO is and compare it to Spacex's stated values?
  15. Three: Even copper corrodes over cosmologically significant time periods (millions of years). Just because something is frozen does not mean it will remain intact and functional ready to be defrosted. I've some professional experience with trying to keep things protected over mere geologically significant time (tens of thousands of years) and I'd say the only hopes lie at a significant fraction of the speed of light. As we can't use the entire mass of the solar system as reaction material you are going to have to find a very large black hole with a shallow gravity well in a quiet neighbourhood (the less the black hole is consuming the lower the radiation/bombardment hazard) and slingshot very close to the event horizon. Of course, finding and travelling to such a black hole will take a cosmologically significant time period, so basically no. Not even a digitally stored simulation of a person's consciousness could be kept over that sort of time period.